Trump’s reputation precedes him. So does Woodward’s.

BOB WOODWARD’S new book, “Fear,” does not paint a different picture of the early Trump White House than the one that has already emerged from credible news organizations in daily reporting on President Trump. Rather, the book fills in details of a presidency led by an ignorant, impulsive and dishonest narcissist — and the people around him who enable or restrain his worst instincts.

Based on hundreds of hours of interviews, Mr. Woodward, a Post associate editor, describes the desperate measures that staff took to prevent the government from descending into chaos. Former National Economic Council director Gary Cohn reportedly swiped documents off Mr. Trump’s desk, which may have kept the United States in the North American Free Trade Agreement and a South Korean trade pact. Perhaps not coincidentally, Mr. Trump has ramped up trade wars against allies and adversaries alike since Mr. Cohn left.

Then there is Defense Secretary Jim Mattis, who apparently complained about the president’s ignorance on foreign affairs and slow-walked unhinged presidential orders until things could cool down. This may have resulted in the United States launching airstrikes to punish Syrian President Bashar al-Assad for using chemical weapons, rather than the bloody rampage Mr. Trump reportedly favored.

These revelations highlight the dilemma facing public-spirited people working in Mr. Trump’s executive branch. The United States would probably be worse off without the service of Mr. Cohn, Mr. Mattis and other adults. But in the long term, does normalizing a man they know is unfit do more damage? Can that service come at the cost of implementing orders only somewhat less absurd than the ones these patriots hope to stop?

The calculation is simpler for senior members of Congress, such as House Speaker Paul D. Ryan (R-Wis.) and Senate Majority Leader Mitch McConnell (R-Ky.), whose role is to check the executive: They have let the president do and say too many outrageous things without serious pushback — and watched as other congressional Republicans abused their oversight authorities to cover for Mr. Trump.

The moral implications of their work should also weigh heavily on the lawyers guiding the president through the investigation of special counsel Robert S. Mueller III. Mr. Woodward recounts how former Trump lawyer John Dowd subjected the president to questioning about the Russia probe in a practice session in preparation for an interview with Mr. Mueller. After a session filled with false statements, Mr. Trump went on an angry 30-minute rant. Mr. Dowd resigned two months later, apparently insistent that Mr. Trump is “not a good witness.” Trump lawyer Rudolph W. Giuliani has since built a legal strategy on publicly trashing Mr. Mueller. Is attacking a lifelong public servant in defense of a man who cannot tell the truth really what Mr. Giuliani wants to be remembered for?

Mr. Trump and other administration officials have attacked the Woodward book. They will have trouble impugning his credibility. Ari Fleischer, former White House press secretary for President George W. Bush and no ally of the mainstream media, tweeted, “I’ve been on the receiving end of a Bob Woodward book. There were quotes in it I didn’t like. But never once — never — did I think Woodward made it up. . . . Woodward always plays it straight.” Mr. Woodward’s reputation precedes him. So does Mr. Trump’s.